湘中拗陷天然气成藏模式与深盆气探索

Xiangzhong depression, a left negative tectonic units of late Paleozoic epicontinental basin in South China , had favorable condition for hydrocarbon pooling. It is an important area of the southern marine gas exploration. There were 18 drilling showing gas well, but it could not obtained commercial oil-gas flow in deep basin. the marine strata in the region is similar with the Sichuan Basin; The sandstone gas-bearing layer of C1d1 in xiangzhong depression is the same as the Jiannan gas field, therefore, deep basin gas had much more accumulation potential. Based on the oil and gas geology, sedimentology, petroleum accumulation Geochronology, The project goes into studing the geological structure in late Paleozoic, the status of typical oil and gas reservoirs, reservoir occurrence and the main controlling factors to establish the pattern of the deep basin gas. If the reservoir is indeed the tight sand gas or deep basin gas (Jiang 1 well), it is possible to find a series of deep basin gas in the deep,and come a breakthrough. This work helps to understand the forming pattern of natural gas in this area in a new perspective. It could provide a reference for the gas accumulation model and exploration prospects in southern China, and also provide evidence for the international scientific issues.

湘中拗陷作为晚古生代南华陆表海盆在湘中的一个负向构造单元，先天成油气地质条件优厚，是中国南方海相天然气勘探的重要领域。目前发生气喷井18口，但中深层天然气研究尚未取得重大突破。区内海相地层与四川盆地具相似沉积环境与地质结构；湘中下石炭统大塘阶石磴子组砂岩含气层性质与中扬子西部鄂西渝东区的建南气田深盆气（建深一井）具可比性，因此，深盆气（保存好，储量大）更具成藏潜力。本项目拟利用石油天然气地质学、沉积学、成藏年代学等方法，研究湘中晚古生代地质结构，剖析典型油气藏地质特征、油气层赋存状况，分析成藏主控因素，确立深盆气成藏发育模式，探索富集规律。若盆内气藏确为致密储集层物性控制或水层对气层封堵（姜一井）等气藏类型，那么就有可能在中、深层发现一系列深盆气藏，形成突破。此举从新的角度认识该区天然气成藏规律，不仅为中国南方天然气成藏模式和勘探前景提供参考，也为解决国际上相关科学问题提供证据。

湘中拗陷作为晚古生代南华陆表海在湘中的一个负向构造单元，先天成油气地质条件优厚，是中国南方海相天然气勘探的重要领域。目前，天然气成藏条件和成藏模式问题在该地区天然气富集成藏研究中较为关键，其中还包括了该区致密砂岩气或者深盆气的成藏潜力研究。我们首先针对该地区典型的残余油气藏开展了成藏模式的解剖、对比，通过野外地质调查、采样，磨片开展镜下观察、薄片分析、流体分包裹体检测，分析研究区天然气成藏影响和控制因素、储层孔隙度演化、天然气充注期次；开展地层对比、录测井资料分析、地震资料对比解释分析构造运动、地层埋藏史及圈闭形成史等问题。获得了天然气成藏的主要控制因素和成藏机理，明确了深盆气成藏模式，指出深盆气为该区潜力勘探目标。